This afternoon PMs stopped working for me. I attempted to respond to a PM I received a couple of hours ago, but have been unable to do so. I make sure I am logged in, click on the link in the notification email, to find I need to log in again. I tried this repeatedly. Then I navigated to the relevant forum thread, and was logged out upon reaching the thread. I logged in again, and when I finally clicked on the other person's name to send a PM, the page informed me that he doesn't have a PM email address set up. He did just a few hours earlier.
Updated with browser details – Using Mobile Safari on newest iOS (5?). These functions have all worked for me until this afternoon.
